LRFD Design Procedure (3rd Edition)
Using LRFD requirements for the calculation of factored forces and the calculation of section capacities, with some modification to account for the different nature of Castellated beams, the following design checks are performed.
Shear on Gross Section
This is done by calculating the maximum shear along the span (this is usually one end or the other) from which the actual shear Vu is calculated and compared with the shear capacity Vn per Eq (F2-1), (F2-2) or (F2-3) based on the h/tw of the gross section, and a phi of 0.9.
Shear on Net Section
This is done by calculating the maximum shear at any hole and splitting the shear between the top and the bottom tees, from which the actual shear Vu is calculated and compared with the shear capacity Vn per Eq (F2-1), (F2-2) or (F2-3) based on the h/tw of each tee individually, and a phi of 0.9.
Horizontal Shear (through web post)
This is done by calculating the worst horizontal shear Vu through any web post and comparing it with the shear capacity Vn per Eq (F2-1), (F2-2) or (F2-3) based on e/tw of the post, and a phi of 0.9. When the top piece is made from a different beam size than the bottom piece, the capacity is based on the thinner of the web thicknesses of the top and bottom pieces. This check is performed for both the precomposite and postcomposite conditions for composite beams.
Web Post Buckling
This is done by calculating the capacity of the web post against a buckling failure, and comparing it to the actual factored forces on the most critical web post. This check is performed for both the precomposite and postcomposite conditions for composite beams.
Lateral Torsional Buckling / Unbraced Length
This check is done for Noncomposite C-Beam™ only. It is not done for Composite C-Beam since they are continuously braced by the deck, nor is it done for the precomposite condition. The bending capacity Mn is based on the gross cross section of the Castellated beam. The conditions of the limit states of Lateral Torsional Buckling, Flange Local Buckling, and Web Local Buckling are checked. The section is not allowed if the web is slender.
Vierendeel Bending
This check examines the combined effects of the bending and axial forces on the top and bottom tees resulting from the shear and moments on the beam. The Vierendeel Bending check is performed on every tee, and is performed for both the precomposite section and the composite section for composite C-Beam. The axial force and bending moment on the tee is calculated. The axial capacity Pn and the bending capacity Mn are based on the properties of the tee. The interaction of the axial force and bending moment with the corresponding capacities is then calculated.